The invention provides a high-intensity low-modulus metastable beta titanium alloy tooth arch wire which is characterized by comprising the following nominal chemical components in percentage by mass: 11 percent of Mo, 3 percent of Nb, 5 percent of Zr, 4 percent of Sn and the balance of titanium and unavoidable impurities. The tooth arch wire provided by the invention has good biocompatibility, high tensile strength, low elastic modulus, a wide elastic range and excellent resilience; moreover, the orthodontic force of the high-intensity low-modulus metastable beta titanium alloy tooth arch wire is lower than that of a stainless steel wire, but is higher than that of a nickel-titanium alloy wire, the elastic modulus of the high-intensity low-modulus metastable beta titanium alloy tooth arch wire is only one fourth to one third of that of the stainless steel wire, and the high-intensity low-modulus metastable beta titanium alloy tooth arch wire has a wider elastic range and a wider orthodontic displacement range than the stainless steel wire. Utilization of the tooth arch wire provided by the invention can obtain the stable and mild orthodontic force and durable and moderate displacement and can realize larger displacement of teeth without replacing an orthopedic wire or only by replacing the orthopedic wire a little.